Complex Oxide Pyrochlores for High-Temperature Thermoelectric Harvesting
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Solution Overview
Problem
Current thermoelectric materials are not environmentally durable and perform poorly at higher temperatures, such as those encountered in aeronautic gas turbine engines, leading to instability and oxidation, which hinders their ability to efficiently convert heat into electricity.
Innovation Solution
Development of complex oxide-based pyrochlores with a chemical formula A2B2O7 that can operate at high temperatures without oxidizing in air, featuring a mixed cation at the B-site, allowing for direct heat-to-electricity conversion in gas turbine engines without the need for special coatings or inert packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermoelectric materials (silicon-based or germanium-based) are used, then heat-to-electricity conversion can be achieved, but the materials oxidize or become unstable in air at higher temperatures (600-700°C or higher)
Solution Approach 1:
The invention changes the chemical composition parameters by using complex oxide pyrochlores with specific A2B2O7 stoichiometry and mixed B-site cations, which fundamentally alters the material's oxidation resistance properties while maintaining thermoelectric functionality at high temperatures
Solution Approach 2:
The invention employs composite oxide structures with multiple cation types at the B-site (e.g., transition metals combined with main group elements), creating a composite material that combines the beneficial properties of different elements to achieve both high-temperature stability and oxidation resistance
2Productivity
If thermoelectric materials operate at higher temperatures in gas turbine engines, then more waste heat can be harvested, but the materials suffer from oxidation and instability
Solution Approach 1:
The complex oxide pyrochlore structure inherently provides an oxidation-resistant environment for the thermoelectric active phases, effectively creating a chemically stable atmosphere that prevents oxidation even in air at high temperatures, eliminating the need for additional protective measures
3Reliability
If thermoelectric materials are protected from oxidation using special coatings or inert packaging, then environmental durability improves, but device complexity increases
Solution Approach 1:
The thermoelectric material itself provides the protection function through its intrinsic oxidation-resistant pyrochlore structure, eliminating the need for separate protective coatings or packaging systems. The material serves both its primary thermoelectric function and its own protection from environmental degradation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The complex oxide-based pyrochlores demonstrate suitable properties like a Seebeck coefficient, electrical resistivity, thermal conductivity, and electronic band gap, enabling effective heat-to-electricity conversion at high temperatures, thus overcoming the limitations of existing materials.
Implementation Method 1
complex oxide based pyrochlores that convert heat into electricity
Data Source
AI summary
An apparatus for solid state energy harvesting includes a complex oxide based pyrochlores having a chemical formula of A2 B2 O7 configured to directly convert heat into electricity and operate and function at a higher temperature without oxidizing in air. The complex oxide based pyrochlores are mixed with cation at B-site.